diff --git a/cellxgene_gateway/filecrawl.py b/cellxgene_gateway/filecrawl.py
index 8a62818..95dc471 100644
--- a/cellxgene_gateway/filecrawl.py
+++ b/cellxgene_gateway/filecrawl.py
@@ -62,5 +62,6 @@ def render_item_tree(item_tree, item_source):
 
 def render_item_source(item_source, filter=None):
     item_tree = item_source.list_items(filter)
-    heading = f"<h6><a href='/filecrawl.html?source={urllib.parse.quote_plus(item_source.name)}'>{item_source.name}</a></h6>"
+    filterpart = "" if filter is None else ":" + filter
+    heading = f"<h6><a href='/filecrawl.html?source={urllib.parse.quote_plus(item_source.name)}'>{item_source.name}</a>{filterpart}</h6>"
     return heading + render_item_tree(item_tree, item_source)
diff --git a/cellxgene_gateway/items/s3/s3item_source.py b/cellxgene_gateway/items/s3/s3item_source.py
index 030c28e..7a93a95 100644
--- a/cellxgene_gateway/items/s3/s3item_source.py
+++ b/cellxgene_gateway/items/s3/s3item_source.py
@@ -61,7 +61,7 @@ class S3ItemSource(ItemSource):
         return self.convert_h5ad_key_to_annotation(item.descriptor)
 
     def list_items(self, filter: str = None) -> ItemTree:
-        item_tree = self.scan_directory()
+        item_tree = self.scan_directory("" if filter is None else filter)
         return item_tree
 
     def scan_directory(self, directory_key="") -> dict: